Board module and fabrication method thereof

Abstract

Affixed to a projection ( 111 ) of a glass substrate ( 110 ) included in a liquid crystal module ( 100 ) are a first ACF ( 150 a ), which has low surface tack strength but high connection reliability, and a second ACF ( 150 b ), which has high component attaching capability attributed to high surface tack strength. With these, an LSI chip ( 130 ), electronic components ( 150 ), etc., are mounted on the glass substrate ( 110 ), so that high-speed electronic component mounting can be achieved while ensuring connection reliability.

The invention claimed is: 
     
       1. A board module having a plurality of electronic components mounted on a substrate via anisotropic conductive films, the module comprising:
 a glass substrate having a plurality of lines formed thereon; 
 a first anisotropic conductive film affixed on the glass substrate; 
 a second anisotropic conductive film or nonconductive film affixed on the first anisotropic conductive film; and 
 electronic components disposed on the second anisotropic conductive film or nonconductive film, subjected to pressure bonding, and thereby connected to the lines at least via conductive particles included in the first anisotropic conductive film, 
 wherein the first anisotropic conductive film has higher connection reliability than the second anisotropic conductive film or nonconductive film, 
 the second anisotropic conductive film or nonconductive film has higher surface tack strength than the first anisotropic conductive film, and 
 the first anisotropic conductive film has a higher melt viscosity than a melt viscosity of the second anisotropic conductive film or nonconductive film at a temperature for thermocompression bonding to connect the electronic components to the lines. 
 
     
     
       2. The board module according to  claim 1 , wherein,
 the first anisotropic conductive film has so high connection reliability that the electronic components can be satisfactorily connected to the lines on the glass substrate, and 
 the second anisotropic conductive film or nonconductive film has so high surface tack strength that the electronic components can be satisfactorily attached at a predetermined speed by a mounter. 
 
     
     
       3. The board module according to  claim 1 , wherein the first anisotropic conductive film has a greater thickness than the second anisotropic conductive film or nonconductive film. 
     
     
       4. The board module according to  claim 1 , wherein,
 the glass substrate includes a display portion for displaying an image, and 
 the electronic components include drive elements for driving the display portion on the basis of externally provided signals. 
 
     
     
       5. The board module according to  claim 1 , wherein the first anisotropic conductive film, and the second anisotropic conductive film or nonconductive film are affixed over a predetermined area including the lines. 
     
     
       6. A board module having a plurality of electronic components mounted on a substrate via anisotropic conductive films, the module comprising:
 a glass substrate having a plurality of lines formed thereon; 
 a first anisotropic conductive film affixed on the glass substrate; 
 a second anisotropic conductive film or nonconductive film affixed on the first anisotropic conductive film; and 
 electronic components disposed on the second anisotropic conductive film or nonconductive film, subjected to pressure bonding, and thereby connected to the lines at least via conductive particles included in the first anisotropic conductive film, 
 wherein the first anisotropic conductive film has higher connection reliability than the second anisotropic conductive film or nonconductive film, 
 the second anisotropic conductive film or nonconductive film has higher surface tack strength than the first anisotropic conductive film, 
 the first anisotropic conductive film has a surface tack strength of less than 185 KPa at room temperature, and 
 the second anisotropic conductive film or nonconductive film has a surface tack strength of greater than or equal to 185 KPa at room temperature. 
 
     
     
       7. A board module having a plurality of electronic components mounted on a substrate via anisotropic conductive films, the module comprising:
 a glass substrate having a plurality of lines formed thereon; 
 a first anisotropic conductive film affixed on the glass substrate; 
 a second anisotropic conductive film or nonconductive film affixed on the first anisotropic conductive film; 
 electronic components disposed on the second anisotropic conductive film or nonconductive film, subjected to pressure bonding, and thereby connected to the lines at least via conductive particles included in the first anisotropic conductive film; 
 a flexible printed circuit board; and 
 a third anisotropic conductive film affixed to the flexible printed circuit board, 
 wherein the first anisotropic conductive film has higher connection reliability than the second anisotropic conductive film or nonconductive film, 
 the second anisotropic conductive film or nonconductive film has higher surface tack strength than the first anisotropic conductive film, and 
 the flexible printed circuit board is connected to the lines at least via conductive particles included in the first and third anisotropic conductive films.